Circuit design of TL494 push-pull output (H bridge DC motor control system based on TL494)

**Abstract:** This paper presents a DC motor control system that utilizes the TL494 as its central component, combined with Pulse Width Modulation (PWM) technology. The H-bridge configuration based on TL494 offers a simplified circuit design, strong driving capability, low power consumption, easy control, and stable performance. These advantages make it ideal for a wide range of applications requiring precise motor control. DC motors are widely used in various fields such as industry, aerospace, and robotics due to their excellent starting, braking, and speed regulation characteristics. With the advancement of power electronics, PWM has become a popular method for controlling DC motor speeds. It provides high accuracy, fast response, a wide speed range, and low energy consumption. The H-bridge driver circuit enables four-quadrant operation of the DC motor, including forward motion, forward braking, reverse motion, and reverse braking. This makes it an essential part of modern DC motor servo systems. **1. Principle of DC Motor PWM Speed Control** As is well known, the speed of a DC motor can be expressed by the formula: $$ N = \frac{V - I_a R_a}{K \phi} $$ Where $ N $ is the motor speed, $ V $ is the applied voltage, $ I_a $ is the armature current, $ R_a $ is the armature resistance, $ K $ is a constant, and $ \phi $ is the flux. Speed control in DC motors can be achieved through excitation control or armature voltage control. While excitation control is rarely used, armature voltage control is more common. With the development of power electronics, changing the armature voltage has become easier, and PWM is one of the most frequently used techniques. PWM works by adjusting the duty cycle—the ratio of the on-time to the total period of the motor's voltage supply. This effectively controls the average voltage applied to the motor, thereby regulating its speed. The core of the PWM system is a voltage-pulse width modulator, which adjusts the pulse width based on the control signal. This allows for precise control of the high-power transistor’s on-time, enabling accurate regulation of the armature voltage. The structure of the voltage-pulse width converter consists of a triangular wave generator, an adder, and a comparator. The triangular wave generator produces a fixed-frequency triangular wave, which is added to the input command signal. The resulting signal is then compared using a comparator. The comparator, operating in open-loop mode, generates a switching signal whose pulse width varies according to the input command. In the typical setup, the negative input of the comparator is grounded, while the sum of the command signal and the triangular wave is applied to the positive input. When the input is zero, the output is at full amplitude. As the input changes, the pulse width of the output signal varies accordingly. The modulation process of the signal waveform is illustrated in Figure 2. The output signal maintains a constant amplitude, but its pulse width changes depending on the command signal. The frequency of the output signal is determined by the frequency of the triangular wave. When the command signal is zero, the output is a symmetrical rectangular pulse. If the command signal is positive, the positive pulse becomes wider; if it is negative, the negative pulse becomes longer. When the command reaches half the peak of the triangular wave, the output becomes a DC signal—either positive or negative, depending on the sign of the command. This PWM technique is highly effective in controlling DC motor speed and is widely used in modern electronic control systems.

Piezoelectric Material

Yuhai piezo materials include : hard piezo material, soft piezo material and lead free piezo material

Soft piezo material exhibits: larger piezoelectric constants, higher permittivity, larger dielectric constants, higher dielectric losses, larger electromechanical coupling factors, low mechanical quality factors, a lower coercive field, poor linearity, and is easier to depolarize. The ideal application of soft piezo materials is sensing needs. Yuhai soft pizeo materials are PZT-5, PZT-5H, PSnN-5 and PLiS-51.

Hard piezo material exhibits: smaller piezoelectric constants, lower permittivity, smaller dielectric constants, lower dielectric losses, smaller electromechanical coupling factors, high mechanical quality factors, a higher coercive field, better linearity, and is harder to depolarize. The ideal application of hard piezo materials is high power transducer needs. Yuhai hard pizeo materials are PZT-4, PZT-8, PCrN-4 and PBaS-4.

Yuhai company developped lead free piezo material BaTiO3 and apply for the Chinese Patent in 2011, to meet the needs of environmental protection in today's society.

Piezoelectric ceramic material

Properties and Classification

General description of material properties	Material Code	Properties	Application
Soft PZT ceramic	PZT-51	Characteristics: larger piezoelectric constants, higher permittivity, larger dielectric constants, higher dielectric losses, larger electromechanical coupling factors, low mechanical quality factors, a lower coercive field, poor linearity, and is easier to depolarize.	low-power ultrasonic transducers
	PZT-52		low-frequency sound transducers
	PZT-53		applications with high g coefficient, for example,
	PZT-5H		microphones,vibration pickups with preamplifier
	PLiS-51		low-frequency vibration measurements
	PMgN-51		Hydrophones, transducers in medical diagnostics
	PSnN-5		Actuators
Hard PZT ceramic	PZT-41	Characteristics: smaller piezoelectric constants, lower permittivity, smaller dielectric constants, lower dielectric losses, smaller electromechanical coupling factors, high mechanical quality factors, a higher coercive field, better linearity, and is harder to depolarize.
	PZT-42		High-power acoustic applications
	PZT-43		Hydroacoustics, sonar technology
	PZT-82		piezomotor
	PCrN-4
	PBaS-4
Lead free piezo ceramic	BaTiO3	Characteristics: Low density, low curie temperature, lead free.	Ultrasonic transducers suitable for low-temperature underwater, for example ultrasonic transducer in fishfinder

Piezoelectric Material,Piezo Ceramic Element,Piezo Electric Cylinder ,Piezo Sphere

Zibo Yuhai Electronic Ceramic Co., Ltd. , https://www.yhpiezo.com